Separation of cobaltite



July 9,1946. J. R. XCIUNNINGHAM 2,403,640

SEPARATION COBLALTITE Filed April 15, 1942 PULP CHALCOPYRITE ACID I eANGUE 7 PYRITE-PYRRHOTITE COBALTITE //v VE/VTOR fl ck/wa minerals ofPatented July '9, 1946- SEPARATION OF COBALTITE Larkspur, Calii.,assignor,

John R. Cunningham,

by mesne assignmen Corporation, San Fr tion of Delaware ts, toCalifornia Research ancisco, Calif., a corpora- Application April 15,1942, Serial No. 439,068-

1 Claim.

This invention relates to the separation of cobaltite from mineralscontaining it. Cobaltite, a mineral position CoAs'S, is an availablecobalt mineral from which the pure'metal or its compounds can ,beeconomically produced, provided, however, the

cobaltite can be separated'in concentrated form of the approximate com-'from other minerals associated therewith. Among the minerals frequentlyassociated with cobaltite are pyrite and pyrrhotite. Chalcopyrite isalso frequently found in association with cobaltite.

Separationof minerals by flotation methods has advanced to the pointwhere almost any min- Other objects achieved by this invention will beapparent from the following description and the appended claim.

I have found that cobaltite can be readily and eilicientlyseparatedi'rom pyrite or pyrrhotite, or from both if present together, bysubjecting the mineral mixture to treatment with lime, and thereaftersubjecting the mixture to flotation in a system of pH not greater thanabout 7 in the presence of a xanthate collector and a depressant for thecobaltite, and floating the pyrite and/or pyreral or group ofmineralscan be separated from any other mineral or group of minerals ofdistinctly different fioatability and flotation characteristics. Thedifliculty arises in separating very similar characteristics.

In the instant case, cobaltite is found associated with gangue (earthymatter of little or no mineral value), pyrite and pyrrhotite and,frequently, with chalcopyrite. The separation of the groupcobaltite-pyrite-pyrrhotite from both the gangue and the chalcopyrite iseasy and straightforward. The gangue canbe'separated byfloatfloatability and flotation ing the minerals in an acid or neutralcircuit, employing the usual flotation agents for flotation of sulfideminerals, whereby the cobaltite-pyrite pyrrhotite are floated and thegangueis rejected. Also, chalcopyrite can be readily separated byfloating it in a basic circuit. The' separation of cobaltite. from thepyrite and pyrrhotite is, however, a problem of wholly differentmagnitude. The floatabilities and flotation characteristics of thesethree minerals are so. similar that, heretofore tomy knowledge, theyhave not been separated except by cumbersome and expensive methods.

It is an object achieved by the present invention toefiect a facile,economical separation of cobaltite from ores, concentrates and the likecontaining it in association with pyrite, pyrrhotite, or other'ironsulfide minerals of similar flotation characteristics.

It is a further and particular object achieved by this invention toseparate cobaltite. from ores, concentrates and the like containing itin associ-' ation with pyrite or with chalcopyrite.

pyrrhotite, or both, together rhotite away from the cobaltite in thissystem of. controlled pH with the aid of the said flotation agents.

Without embarking upon any detailed scentific explanation of thephenomena involved, or in any way limiting the invention to a theory, Ibelieve that the delicate separation of cobaltite from pyrite and/0rpyrrhotite thus efiected is due in large part to pre-liming the mineralmixture, which depresses the cobaltite more effectively and more durablythan it depresses the pyrite and pyrrhotite, so that when the system issubsequently neutralized or acidified, the cobaltite is still depressedbut the pyrite and pyrrhotite are not depressed orare not as fullydepressed as the cobaltite. Upon flotation treatment in a system of pHnot greater than about 7 in the presence of a xanthate collector (aknown class of collectors suitable for use with sulfide minerals) and adepressant for the cobaltite (of which many wellknown examples areavailable as hereinafter described), the cobaltite is still,substantially nonfioatable but the pyrite and pyrrhotite are flotable,especially in the presence of an activator.

If the mineral mixture consists of cobaltite plus pyrite and/orpyrrhotite, and no more, only the single flotation step described isnecessary, and.

this step may be repeated, subjectingthe cobaltite reject and thepyrite-pyrrhotite floated mixture each to a further similar flotationtreatment.

' However, if, as is usually the case, gangue is present, or if, as isoften the case, chalcopyrite is present, in the mineral mixture, apreferred modification is employed. A single illustration with respect,toja chalcopyrite-gangue-cobaltitepyrite-pyrrhotite ore will suflicetoillustr'ate this 1 preferred modification.

ore, suitably comminuted, will mixing with lime water, mix- In such casethe first be liined, as by accomplished in the usual way,

- Preferably, the frothing ample,'as that described ed in cell 2 and Thereject or-tailings. containing the cobaltite.

mam

3 ing dry lime with the ground ore and. adding water, or otherwisemaking an alkaline pulp containing lime. The chalcopyrite is thenfloated. Any other mineral flotable in a basic circuit may likewisebefloated. This flotation step may be as by the use of pineoil asfrothing agent and potassium ethyl xanthate as collector. The reject ofgangue, cobaltite, pyrite and pyrrhotite, in pulp condition, is thenrendered approximately neutral to acid and the mixture'is subjected toflotation in the presence of a xanthate collector to float thecobaltite, pyrite and pyrrhotite away from the gangue. cobaltite is alsofloated. This is possible because It will be noted that in this step thethe cobaltite depressant has not been used. The next step involves theuse of a xanthate collector and a cobaltite depressant, whereby thecobaltite is depressed and rejected and only the pyrite and pyrrhotiteare floated, as described above with reference to a simplecobaltite-pyrite-pyrrhotite mixture.

In themore complex separation of cobaltite from an o're containing it inassociation with chalcopyrite, gangue, pyrite and pyrrhotite, as justdescribed, the order of steps is highly important. It is important thatthe chalcopyrite be floated first in a basic circuit and that gangue besubsequently separated. I have found that if the gangue is firstseparated and the chalcopyrite or other like mineral is then separated,the flotation products and tailings in subsequent separation steps arecontaminated with chalcopyrite. This difficulty is avoided by followingthe order of steps as described above.

Of course, if chalcopyrite and gangue are separated by other means, orif a mineral mixture is available which does not contain chalcopyrite organgue, the procedure of the invention may be suitably modified orsimplified.

The process of my invention will be more fully agrammatic drawingrepresenting a process of separating cobaltite from an ore containing itin association with chalcopyrite, gangue, pyrite and pyrrhotite.

Referring to the single figure of the drawin an ore comprisingchalcopyrite. pyrite, pyrrhotite. cobaltite and gangue, suitably groundand made into a pulp (about 20-30% solids) and made alka-' line withlime solution. is introduced through a conduit i into a flotation cell 2and is therein subjected to flotation in the presence of afrothing'agent such as pine oil and a collector such as potassium ethylxanthate. The frothing agent and collector may be added separately tothe floreject or tailings of gangue is withdrawn through 8 long enoughto clean and brighten the surface of the sulfide particles. The. pulp,thus adjusted as to pH. is withdrawn through a conduit 1 and introducedinto a flotation cell 8 where it is subjected to flotation in thepresence of suitable quantities of a frother, such as pine oil, and axanthate collector. such as amyl xanthate, or potassium amyl xanthate,whereby all of the sulfide minerals, that is. pyrite, pyrrhotite andcobaltite. are floated and the gangue is rejected. The

a conduit 9 and suitably disposed of, and the floated sulfides arewithdrawn through a conduit l0 and introduced to a flotation cell llSuitable quantities of a frother, such as pine oil, a xanthatecollector, such as amyl xanthate, a depressant for cobaltite, such asmono calcium aryi sulfonate, and an activator, which may be a heavymetal salt, such as ferric sulfate, along with sufficient water to forma suitable pulp, are added and the mixture is subjected to flotation.whereby the pyrite and pyrrhotite are floated and the cobaltite isrejected. If need be, more acid may be added to adjust the pH of thepulp to 7 or less. Maintenance of the pH in this and the followingflotation step at 'l or less, preferably from 7 to 4, is especiallyimportant because the difference in floatability. between cobaltite onthe one hand and pyrite and pyrrhotite on the other hand is small. Bymeans of careful control of pH' and proper selection of flotationagents,- I am'able' successfully to float the pyrite and pyrrhotite awayunderstood by reference to the accompanying difrom the cobaltite despitethis small difference in floatability. The cobaltite reject or tailingsis removed through a conduit l2 and the floated pyrite and pyrrhotiteare removed through a conduit l3 and introduced into a flotation cellIt. Suitable quantities of the same reagents as used in cell H, andof-water and/or acid if need be. are introduced into cell ll and thepyritd-pyrrhotite concentrate is subjected therein to a second flotationsimilar to that carried out in cell l I. thus producing a furtherquantity of cobaltite as reject or tailings and floating a purerpyrite-'pyrrhotite concentrate. The latter concentrate is removedthrough a conduit I5 and the recovered cobaltite is removed through aconduit IB and joined with the first portion of cobaltite concentrateremoved through conduit 12.

In the preferred embodiment illustrated by the drawing and describedabove, thepyrite-pyrrhotite-cobaltite concentrate resulting fromtheseptation cell, or maybe incorporated in the ore or pulp before it isintroduced into the flotation cell. agent is added to the pulp in theflotation cell. The flotation step car-,

ried out in cell 2, and subsequent flotation steps hereinafterdescribed, may be carried out in acalong with pyrite, pyrrhotite andgangue, is withdrawn through a conduit 4 and introduced into aconditioning vessel 5 to which an acid. such,

for example, as sulfuric acid or hydrochloric acid, is added through aconduit, in quantity suflieient to adjust the pH of the pulp to about 4to '1. The,

material is preferably held in conditioning vessel ture. orin thechalcopyrite separation may be pure or impure lime.

aration of game in flotation cell 8 is subjected to a double flotationas shown, but instead of this, a single flotation step, or three or evenmore flotation steps, may be employed. Thus the cobaltite concentratemay be subjected to further flotation to separate any residue of pyriteor pyrrhotite therein and the pyrite-pyrrhotite concentrate y recoverany residue of cobaltite therein.

The lime used in pretreating the mineral mix- For. example. it may be adolomitic lime. The acid used in the neutralizing or acidifying steps ispreferably sulfuric acid. but other acids capable of producing thedesired pH. such ashydrochloric and phosphoric acids, I

may. be used.

Following are frothing. collecting, activating and 'depressin agentscapable of use in accordance with myinvention, these specific examplesbelonging to rdco classes of flotation agents; many of likewise besubjected to further flotation to specific examples of suitable 811M 7which set forth in Gmidins "Principles of asoaeso Frothing agents (page363):

Pine oil Higher alcohols Fuse] oil Cresylic acid Eucalyptus oil CamphorCollectors (page 371) Amyl xanthate Butyl xanthate Propyl xanthate Ethylxanthate Sodium and potassium salts of the above xanthates Sulfonatedpetroleum sludge Activators (pages 395 and 396):

Ferric sulfate Lead, nitrate Lead chloride Copper sulfate Copperchloride Cobaltite depressants (pages 393 and 394) Mono calcium arylsulfonate Mono sodium aryl sulfonate Sodium sulfide Sodium cyanideSodium silicate The amounts of such agents that may be used may varyconsiderably. However, in floating pyrite, Pyrrhotitc and cobaltite awayfrom the gangue, in floating pyrite and pyrrhotite away from cobaltite,and in refloating the pyritepyrrhotite concentrate, I prefer to use theagents in the following approximate proportions:

, LbJtonof ore I Ll'lotation of pyrite,- pyrrhotite and cobaltite awayfrom 8 81-1 Brother, such as pine oil 0.3 to 0.2 Xanthate collector,preferably amyl xanthate e 0.25 to 0.75 II. Flotation of pyrite andpyrrhotite away from cobaltlte: Frother, such as pine oil 0.5 to 0.1Xanthate collector preferably amyl xanthate 0.25 to 0.5 Depressant forcobaltite. such as mono calcium aryl sufonate--- 0.25 to 0.5 Activator,such as ferric sulfate-.. 1 to 2 6 LbJton of ore III. Reflotation ofpyrite-pyrrhotite concentrate: Frother, such as pine oil 0.5 to 0.1Collector, preferably amyl xan thate 0.1 to 0.25 1 Depressant forcobaltite, such as mono calcium aryl sulfonate 0.25 to 0.5 Activator,such as ferric sulfate- 0.5 to 2 The depressants used in accordance withmy invention are of the type of non-floating dispersing agents. Theirfunction, as stated, is to depress the cobaltite. They accomplish thisresult by selectively wetting the surface of the cobaltite particles,thereby inhibiting bubble attachment to and flotation of the cobaltiteparticles. The activators, which are preferably heavy metal salts, havethe effect of promoting the'ac'tion of the collecting agents. Theyappear to eflect this result by preferential adsorption of the heavymetal ion, e. g. ferric ion, on the pyrite and pyrrhotite particles, andforming heavy metal xanthate, e. 'g.

. ferric xan'thate.

: I claim:

In a method of efi'ecting separation of cobaltite' from a pulp mixturethereof with chalcopyrite. gangue', and from iron sulfide minerals ofsimilar floatability'to the cobaltite: that sequence of steps whichconsists in first rendering the pulp mixture alkaline with lime; addinga frother and a collector comprising a xanthate, and subjecting vsaidpulp to a first froth flotation to float said chalcopyrite from saidgangue, iron sulfide minerals and said cobaltite; then adding. acid toad- Just the pH of the reject of gangue, iron sulfide minerals andcobaltite to a value not greater than about 7 and a collectorcomprisinga xanthate; then subjecting the pulp thusformed to a secondfroth flotation to float the cobaltite and iron sulfide minerals fromthe gangue; then adding to the cobaltite and iron sulfide a depressantfor the cobaltite a collector comprising 9. mnthate, and an activatorfor the iron sulfide minerals comprising a' heavy metal salt; andsubjecting the pulp thus formed to .a third froth flotation to floatsaid iron sulfide minerals from said cobaltlte in the presence of saiddepressant.

JOHN R. CUNNINGHAM.

